With energy demand greater than ever, machinists in this buoyant sector are finding that investment really does pay dividends. Steed Webzell reports. (This is an extended version of a feature first published in Machinery magazine, February 2010).
With the cold weather in January bringing some curt questions about the apparent lack of UK gas reserves, the campaign for greater renewable energy resources moved from environmental hot potato to a matter of national concern.
Fortunately, the announcement by the UK's Crown Estate (seabed owner) on 8 January revealing the successful bidders for the exclusive Round 3 'Zone Development Agreements' came in the nick of time to dispel any accusations of government procrastination.
Offshore wind farms at Moray Firth, Firth of Forth, Dogger Bank, Hornsea, Norfolk Bank, Hastings, Isle of Wight West, Bristol Channel and Irish Sea will see the current installed capacity of around 4 GW climb enormously.
With this in mind, it is evident that machining opportunities in the offshore wind sector are likely to be significant in the near future. However, in reality it's only the companies that have the required expertise, manufacturing technologies and processes in place that will be able to exploit the potential of the renewable energy sector. Sheffield-based precision sub-contractor Barker Collins Engineering Ltd is one such company.
The company's relocation to a purpose-built 45,000 ft2 facility, plus strategic and regular investment in CNC machine tool technologies, including the recent installation of five Doosan DB 130C/CX horizontal boring machines supplied by Mills CNC, demonstrate Barker Collins' intent.
Image: Barker Collins
"Renewable energy is important to our future growth and development, and we're doing everything we can to ensure that we're well positioned to secure a good percentage of the manufacturing contracts when they come on stream," says Chris Carter, managing director at Barker Collins. But it's not all about what may happen in the future, because Barker Collins is already involved in manufacturing offshore wind turbine components. An example of the type of work undertaken is the production of clevis joints.
Manufactured from cast steel, supplied in sets (one male and one female part per set) and weighing up to 2.5 tonnes each, the clevises are machined on Barker Collins' Doosan horizontal boring machines in a single set-up. Manufacturing times vary, but are typically around 11-13 hours per part. With repetitive motion and longevity key to successful wind turbine operation, hard materials are specified for certain components. This is good news for innovative cutting tool companies able to demonstrate productivity gains and extended tool life.
Among their number is Ceratizit, which says it recently helped a manufacturer of drive shafts for wind turbines, which are manufactured from steel forgings with high chrome and nickel contents, reduce cycle times by 20 per cent, while at the same time increase tool life by 15 per cent. Using a CTC1125 carbide grade square insert, this particular customer was able to run at 55 m/min surface speed (up from 45 m/min) at a feedrate of up to 1.5 mm/rev and depth of cut up to 18 mm. In addition to turning, Ceratizit has a range of milling cutters that are proving productive when machining some of the larger components found in wind turbines. A recent example is the manufacture of 'yaw plates' from flame- cut St.52-3 tool steel. After reviewing the application, Ceratizit proposed its close pitched A251 series milling cutter along with the free-cutting M31 geometry on some CTC5235 grade inserts. The result was an increase in tool life of 50 per cent and an overall improvement in productivity of 33 per cent.
Image: Ceratizit - renewable energy
It may surprise many to learn that wind power is only the second largest source of renewable energy in the UK. The honour of leading renewable goes to biomass.
Again, manufacturing technology companies with the development prowess in place are already benefiting from new orders. A case in point is Mollart Engineering, which has produced its first 18-axis, 16-spindle gundrilling centre able to produce up to 16 holes simultaneously. The new machine is capable of producing up to 36,000 radial holes automatically in a tubular die blank, at the rate of almost 1,000 holes per hour. It is to be used in the production of wooden pellets as part of a biomass green energy project that will make use of scrap wood that is initially shredded and mixed with sawdust and water before being pumped into the centre of the die.
Image: Mollart - oil industry
Conventional energy markets such as oil and gas continue to prove lucrative for companies with proven levels of expertise and investment. Mollart says its recent investment of more than £3.5 million in multi-axis machining technology by Mollart Engineering has enabled the business to capitalise on demand from the oil sector. The money included almost £2 million on three Integrex 300-IIY turn-mill centres from Yamazaki Mazak.
Mollart has since won a series of contracts for the continuous supply of a range of 'wire-line' components through its expertise in deep hole drilling. So demanding are the titanium components, the company has to meet almost perfect drilling standards for roundness and hole straightness, while maintaining very close pitch centres and achieving very thin wall sections over length to diameter ratios on parts up to 140 mm diameter by 1.6 m long.
Another critical process in the production of oil and gas industry parts is EDM, as Dundee-based sub-contractor GA Engineering can testify, following the recent installation of a CUT 30 wire EDM from Agie Charmilles to produce components such as valves, seals, actuators, rings, housings and pumps.
Image: GA Engineering
"We had increased our turning and milling capabilities over recent months by investing in large capacity lathes and heavy duty machining centres, but our EDM capability, in comparison, was letting us down and creating production problems," says Gordon Deuchars, GA's managing director. "Prior to the CUT 30 investment, we had to either sub-contract this type of work or attempt to machine the required part features using conventional machine tool technology. By bringing our large EDM machining capabilities in-house and up to speed, we have improved our performance, our profitability and our competitiveness."
Sandvik Coromant offers advice to those involved in the machining of wind turbine parts. Components such as the hub, planetary carrier and frame have sufficient features to ordinarily fill a magazine with tools. However, recent developments have seen major transformations in milling cutters specifically, says the company, making them suitable for operations that have reduced cutting time, the tool types needed and quality inconsistency.
For instance, machining inside the hub can be difficult and time consuming. One proven, cost efficient solution is back facing with high precision using the CoroMill 331 multi-purpose side and face cutter.
Similarly, with its light cutting action, eight cutting edges and shims to protect the cutter body, the CoroMill 345 is said excellent for face milling operations on hubs. Step and chamfer drilling with a tailor made CoroDrill 880 ensures two machining sequences are made in one with immediate results in machining time and production cost.
Image: CoroDrill 880
The complex shape of the hub makes workholding difficult and as a result, vibration can also be an issue. A combination of Coromant Capto and Silent Tools dampened adaptors is an increasingly popular productivity solution: Coromant Capto for its stability and Silent Tools to avoid vibration when long tools are required to access awkward areas.
Regarding the machining of planetary carriers, manufactured typically from nodular cast iron, Sandvik Coromant's T-MAX P insert are recommended. Here, metal removal at high cutting data under dry conditions is made possible with a combination of hard substrate and wear resistant coating.
The planetary carrier can be machined in different ways, depending on the machine and machining strategy. Helical interpolation, a flexible 3-axis ramping technique, is preferred by many, and with the CoroMill 390 long edge indexable insert cutter, it becomes a truly efficient rough boring alternative, while for fine/finish boring CoroBore 825 is recommended as it is versatile and easy to use with micro adjustments.
Image: CoroBore 825
The main shaft in a wind turbine is a large component where often some 40 per cent of the material is removed from blanks weighing several tons. From a machining point of view, the forged surface demands inserts with secure performance and high temperature resistance due to the long contact times. Here, Sandvik Coromant's WMX wiper is increasingly popular at performing heavy duty turning operations, from forged skin to close tolerance finishing at high metal removal rates.
For the main shaft, a week of machining is not unusual, with different roughing and turning operations as well as drilling – short and deep holes. Here, the application of suitable toolholders, insert geometry and grades has a direct effect on the hours the shaft stays on the machine, the quality consistency achieved for each operation and the tool economy. CoroDrill 800 and T-Max are indexable drills that offer a productive solution for deep holes with high levels of hole straightness and surface finish.
Image: Wind power
In fact, several wind power components have large numbers of holes. The connecting rings in the tower, for instance, often involve drilling hundreds of thousands of holes per year as these components are frequently made in large series. Bolt holes are a basic design feature that are easy enough to achieve and as such are susceptible to broad competition. Best practice is therefore vital because having the latest indexable drill applied correctly can half the the exisiting drilling time in many machine shops.
Just by exchanging a conventional drill with a CoroDrill 880, it is possible to double the number of drilled holes in the same amount of time when manufacturing connecting rings. CoroDrill 880's step technology gives outstanding cutting force balance, providing significant improvements in productivity as well as quality.
A large European connecting ring producer has recently witnessed the benefits of CoroDrill 880 first hand. A constant issue for the company was vibration in the hole making operation. Sandvik Coromant implemented CoroDrill 880 to optimize the process, which not only reduced vibration substantially but also cut cycle time by 35 per cent.
Large metrology solutions
Rainford-based Welding Units UK has been providing connector and flange solutions to oil and gas customers for more than 40 years. Used to connect sub-sea pipelines, the risk of failure in use could have disastrous financial and environmental consequences. To this end, the company's products are inspected at all stages of manufacture. Here, the recent purchase of a UniCal universal digital caliper from Bowers Metrology is proving extremely useful.
Image: Bowers UniCal
As the company produces flanges of up to 2 m in diameter, containing a range of close tolerance features, conventional large scale calipers often prove too heavy and cumbersome to allow the company's employees to achieve the required levels of precision.
"Although the UniCal has the same measuring capacity as some of the company's existing calipers, because it's manufactured from advanced composites, it is only a fraction of their weight, enabling our staff to achieve higher levels of accuracy, while considerably reducing operator fatigue," he says.